Native Hbase access improvments

Native hbase access via Trafodion SQL engine now utilizes the enhancements
made for Trafodion table like pushing mutliple rows to JNI and pre-fetch.
Also removed the dependency on the ResultIterator for the native hbase access.
This reduces yet another object created in HTableClient and improves java
memory usage on the client side.

Cleaned up state changes in the HBase access operators and removed
redundant code in the JNI layer.

Change-Id: I70ab52917aac64b68b3816b8ad834842a4d8745e